Let EC J-PAKE work with custom curves

Author: peterdettman

core/src/main/java/org/bouncycastle/crypto/agreement/ecjpake/ECJPAKECurve.java

@@ -18,7 +18,7 @@
  */
 public class ECJPAKECurve
 {
-    private final ECCurve.Fp curve;
+    private final ECCurve.AbstractFp curve;
     private final ECPoint g;
 
     /**
@@ -116,7 +116,7 @@ public ECJPAKECurve(BigInteger q, BigInteger a, BigInteger b, BigInteger n, BigI
      * groups in {@link ECJPAKECurves}.
      * These pre-approved curves can avoid the expensive checks.
      */
-    ECJPAKECurve(ECCurve.Fp curve, ECPoint g)
+    ECJPAKECurve(ECCurve.AbstractFp curve, ECPoint g)
     {
         ECJPAKEUtil.validateNotNull(curve, "curve");
         ECJPAKEUtil.validateNotNull(g, "g");
@@ -127,7 +127,7 @@ public ECJPAKECurve(BigInteger q, BigInteger a, BigInteger b, BigInteger n, BigI
         this.g = g;
     }
 
-    public ECCurve.Fp getCurve()
+    public ECCurve.AbstractFp getCurve()
     {
         return curve;
     }
@@ -159,7 +159,7 @@ public BigInteger getH()
 
     public BigInteger getQ()
     {
-        return curve.getQ();
+        return curve.getField().getCharacteristic();
     }
 
     private static BigInteger calculateDeterminant(BigInteger q, BigInteger a, BigInteger b)

core/src/main/java/org/bouncycastle/crypto/agreement/ecjpake/ECJPAKECurves.java

@@ -1,7 +1,7 @@
 package org.bouncycastle.crypto.agreement.ecjpake;
 
-import org.bouncycastle.asn1.nist.NISTNamedCurves;
 import org.bouncycastle.asn1.x9.X9ECParameters;
+import org.bouncycastle.crypto.ec.CustomNamedCurves;
 import org.bouncycastle.math.ec.ECCurve;
 
 /**
@@ -37,13 +37,14 @@ public class ECJPAKECurves
 
     static
     {
-        NIST_P256 = fromX9ECParameters(NISTNamedCurves.getByName("P-256"));
-        NIST_P384 = fromX9ECParameters(NISTNamedCurves.getByName("P-384"));
-        NIST_P521 = fromX9ECParameters(NISTNamedCurves.getByName("P-521"));
+        NIST_P256 = getCurve("P-256");
+        NIST_P384 = getCurve("P-384");
+        NIST_P521 = getCurve("P-521");
     }
 
-    private static ECJPAKECurve fromX9ECParameters(X9ECParameters x9)
+    private static ECJPAKECurve getCurve(String curveName)
     {
-        return new ECJPAKECurve((ECCurve.Fp)x9.getCurve(), x9.getG());
+        X9ECParameters x9 = CustomNamedCurves.getByName(curveName);
+        return new ECJPAKECurve((ECCurve.AbstractFp)x9.getCurve(), x9.getG());
     }
 }

core/src/main/java/org/bouncycastle/crypto/agreement/ecjpake/ECJPAKEParticipant.java

@@ -107,9 +107,7 @@ public class ECJPAKEParticipant
      */
     private String partnerParticipantId;
 
-    private ECCurve.Fp ecCurve;
-    private BigInteger ecca;
-    private BigInteger eccb;
+    private ECCurve.AbstractFp ecCurve;
     private BigInteger q;
     private BigInteger h;
     private BigInteger n;
@@ -255,8 +253,6 @@ public ECJPAKEParticipant(
         this.password = Arrays.copyOf(password, password.length);
 
         this.ecCurve = curve.getCurve();
-        this.ecca = curve.getA();
-        this.eccb = curve.getB();
         this.g = curve.getG();
         this.h = curve.getH();
         this.n = curve.getN();

core/src/test/java/org/bouncycastle/crypto/agreement/test/ECJPAKEUtilTest.java

@@ -18,7 +18,6 @@
 public class ECJPAKEUtilTest
     extends TestCase
 {
-    private static final BigInteger TEN = BigInteger.valueOf(10);
     private static final BigInteger ONE = BigInteger.valueOf(1);
 
     public void testValidateParticipantIdsDiffer()
@@ -217,7 +216,7 @@ public void testValidateZeroKnowledgeProof()
         }
 
         // (x,y) elements for Gx are not in Fq ie: not in [0,q-1]
-        ECCurve.Fp curve = (ECCurve.Fp)curve1.getCurve();
+        ECCurve.AbstractFp curve = curve1.getCurve();
         try
         {
             ECPoint invalidGx_1 = curve.createPoint(ONE.negate(), ONE);